1. Field of the Invention
The present invention relates to an improvement in image stabilizing apparatus and image blur detection system which detects the amount of vibration of a camera with respect to the absolute space and drives a correction optical system in accordance with the output thereof to prevent hand vibration at the time of taking a picture.
2. Related Background Art
In a known apparatus of this type, the amount of angular displacement with respect to the absolute space has been detected using an angular displacement sensor, such as disclosed in U.S. Ser. No. 619,906 (filed on Nov. 28, 1990), which is adapted to use inertia of a liquid and control the current to be conducted to a coil in a magnetic field. Hand vibration by a photographer is prevented in accordance with the output from the angular displacement sensor such that a variable vertical angle prism using refractive index of such liquid as disclosed in Japanese Patent Laid-Open Application No.2-59718 is attached to the front surface of the taking lens, or that, as disclosed in U.S. Ser. No. 626,985 (filed on Dec. 13, 1990), the so-called shift optical system which is driven to shift a portion of a taking lens in an up and down and a left and right directions.
Of the characteristics of the correction optical system to be used in the conventional example as described, the frequency characteristic differs, however, by each individual unit due to variance in the processing accuracy and attaching precision of the mechanical components thereof. There have thus been such problems as that, when each system is closed under the same condition to perform feedback control, a vibration of the system as a whole may occur or that control characteristic may be worsened as the effect of friction is large due to reduction in loop gain.
Further, with respect to the angular displacement sensor to be used as the vibration detection means, the frequency characteristic thereof is conventionally determined such that an electric current is conducted through a coil positioned in magnetic field formed by a floating body magnetized in a certain direction and a yoke, so as to vary the conducted current in accordance with the relative angular displacement output to be detected.
Therefore, the characteristic of each individual angular displacement sensor is caused to vary largely by such variances as of the strength of the magnetic field of the magnetized floating body, the accuracy in the processed size of yoke and floating body, the attaching precision of the coil, and the current value of the coil. There has thus been a problem that, if nothing is done, it is very difficult to maintain the stabilizing characteristic of each of the mass-produced cameras at its optimal state.